JPH039584Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an electromagnetic control valve that linearly controls pressure fluid flowing from a high-pressure side flow path to a low-pressure side flow path in accordance with a control current applied to a solenoid. It is something.

<Prior Art> In general, a vehicle speed-sensitive power steering device that linearly controls steering force according to vehicle speed, etc., uses the discharge pressure from a supply pump 1 driven by an automobile engine as shown in FIG. The oil flow rate is controlled to a constant flow rate by a flow rate control valve 2 operated according to the front and rear pressure of the metering orifice 3, and the pressure oil P controlled at this constant flow rate is sent to the servo valve 4 of the power steering device and the electromagnetic control valve. 6, servo valve 4 and power cylinder 5
The ports A and B of the left and right chambers of
By connecting the flow path to the tank T on the low pressure side and applying a control current according to the vehicle speed, etc. to the solenoid of the electromagnetic control valve 6 via the computer 7, a signal such as vehicle speed is applied to the high pressure side flow path. The pressure fluid flowing from the pump to the low-pressure side flow path is linearly controlled.

As shown in FIG. 4, for example, the electromagnetic control valve 6 includes a cylindrical spool 20 slidably fitted into an inner hole 11 of a valve body 10, and a bypass slit 21 at one end of the spool 20. A first flow path P1 is formed in the valve body 10 by being cut out in the radial direction.
A first port 12 communicating with the first port 12 and a second port 13 communicating with the second flow path P2 are provided, and the spool 20 is biased in a direction to close communication between the first and second ports 12 and 13. A control current is applied to the spring 25 according to the vehicle speed, etc., and the spool 20 is moved to the first port 12, the second port 12,
This structure includes a solenoid 29 that attracts air in the direction of communication with the air conditioner 13.

<Problems to be solved by the invention> In such an electromagnetic control valve, the slit 2
Also when the pressure fluid flows from the first flow path P1 to the second flow path P2 due to the influence of the pressure fluid flowing through the flow path P1,
Also, when flowing from the second flow path P2 to the first flow path P1, the flow force acts in the direction of narrowing the opening degree of the slit 21, and as shown in FIG. 5, when the opening degree is constant 01, the flow force By the action of , the opening is narrowed to 02 and the bypass flow rate Q for the control current
is affected, causing an imbalance in the pressure (steering force) generated when the steering wheel is turned to the left and to the right.

<Means for Solving the Problems> The present invention was made to solve the above-mentioned conventional problems. A pressure introduction hole applied to the outer peripheral surface is provided in either or both of the valve body and the spool.

<Operation> The present invention uses the pressure of high-pressure fluid applied to one side of the spool in the radial direction from the pressure introduction hole to press the spool against the wall of one side of the inner hole of the valve body, and applies a force corresponding to the gear generated pressure. This creates sliding resistance on the spool and locks it at a constant opening.

<Example> Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2. FIG. 1 shows a first embodiment of the present invention, in which 10 is a valve body made of a magnetic material. A cylindrical spool 20 is slidably fitted into the inner hole 11 of the valve body 10. Further, the valve body 10 has a first port 12 communicating with the first flow path P1, and a second port 12 communicating with the second flow path P2.
A port 13 is provided, and a bypass slit 21 is cut out in the radial direction at one end of the spool 20 to communicate the first port 12 and the second port 13. 25 is a spring that biases the spool 20 in the direction of closing the communication between the first port 12 and the second port 13; 29 is a spring to which a control current is applied depending on the vehicle speed, etc.; This is a solenoid that sucks the spool 20 and makes the first port 12 and the second port 13 communicate with each other.

In the above configuration, when the first flow path P1 is on the high pressure fluid side and the pressure fluid flows from the first flow path P1 to the second flow path P2, the spool 20 is attached to the valve body 10 near the first port 12. A pressure introduction hole 30 is provided toward the outer diameter surface of the tube.

Further, the pressure fluid may not only flow from the first flow path P1 to the second flow path P2, but may also flow in the opposite direction from the second flow path P2 to the first flow path P1. In such a case, in addition to the pressure introduction hole 30 provided in the valve body 10 as in the second embodiment shown in FIG. are provided in the radial direction. This pressure introduction hole 31 communicates with an inner hole 18 penetrated through the center of the spool 20 and communicating with the second port 13 .

In the electromagnetic control valve configured as described above, when no current is applied to the solenoid 29, the suction force of the solenoid 29 on the spool 20 is zero;
The space between the first port 12 and the second port 13 is closed by the biasing force of the spring 25. When a control current is applied to the solenoid 29, the spool 20 is attracted in the opening direction through the first port 12 and the second port 13 according to the current value, and the spool 20 is drawn in the opening direction through the first port 12 and the slit 21 of the spool 20. Opening degree is controlled linearly.

Here, in the case of the first embodiment shown in FIG.
A part of the high pressure fluid on the first flow path P1 side of the pressure fluid flowing from the flow path P1 to the second flow path P2 is connected to the pressure introduction hole 30.
The pressure is applied to the outer diameter surface of the spool 20. This applies a radial pressing force to the spool 20, presses the spool 20 against the wall surface of the inner hole 11, generates sliding resistance on the spool 20, and locks the spool 20.

Further, the pressure fluid is transferred from the second flow path P2 to the first flow path P.
1, a part of the high-pressure fluid is introduced into the pressure introduction hole 31 shown in the second embodiment of FIG. 2, and pressure is applied to the wall surface of the inner hole 11 of the valve body 10.
As a result, the spool 20 is pushed in the radial direction by a reaction force, and the outer diameter of the spool 20 on the side opposite to the side where the pressure introduction hole 31 is opened comes into pressure contact with the wall surface of the inner hole 11, and slides onto the spool 20. A resistance is generated to create a locked state, and a constant opening degree is maintained according to the control current value.

<Effects of the invention> As described above, the present invention introduces the pressure fluid on the high-pressure side to be bypassed, especially the pressure generated by the gear in the power steering device, to one side of the spool in the radial direction through the pressure introduction hole. The spool is pressed against the wall of one side of the inner hole of the valve body by force, and the sliding resistance generated by that force locks the spool, so that the flow force narrows the opening of the spool. The spool does not move even when the valve is actuated, the opening degree is maintained at a constant level, and the control characteristics are stabilized because it is no longer affected by the bypass flow rate, which has the advantage of balancing the steering force when turning left and right.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a first embodiment of the present invention, Fig. 2 is a sectional view showing a second embodiment of the invention, and Fig. 3 is a hydraulic system of a power steering device in which an electromagnetic control valve according to the invention is used. 4 is a cross-sectional view of a main part of a conventional electromagnetic control valve, and FIG. 5 is a graph illustrating problems caused by the conventional electromagnetic control valve. 10... Valve body, 11... Inner hole, 12...
First port, 13...Second port, 21...Slit, 25...Spring, 29...Solenoid, 30, 31...Pressure introduction hole.

Claims (1)

[Scope of utility model registration request] The valve body has two ports that respectively flow into two channels through which high-pressure fluid and low-pressure fluid selectively flow, and a valve body that forms an inner hole through which these two ports open, and can slide into this inner hole. a cylindrical spool that is fitted into the spool and has a bypass slit cut out in the radial direction at one end that connects the two ports; a spring that biases the spool in a direction that closes communication between the two ports; In an electromagnetic control valve, the solenoid is provided with a solenoid to which a control current is applied according to vehicle speed, etc., and which attracts the spool in a direction that communicates the two ports in accordance with the control current, the solenoid being connected to either one of the two ports. ,
An electromagnetic control valve comprising a pressure introduction hole provided in one or both of the valve body and the spool for applying the high-pressure fluid to the outer peripheral surface of one side in the radial direction of the spool.